Spotting deforestation from space

São
Tomé and Príncipe, a small island positioned in the gulf of Guinea, is
considered one of the 200 most important biodiversity hotspots in the world. Manyof its important
species and their habitats are threatened. Until recently very little
information was available or known about deforestation and ecosystem loss.
Earth observation has proved a powerful tool to learn about the process of
deforestation and to spot the places
where interventions are needed the most.

Sao Tome and Principe hosts an extraordinary amount of
endemic bird and plant species[1]
for an island of its size. The island has a large protected area, the Obo National
park, which covers around 35 per cent of
the country's surface. Signs of deforestation in the park and its buffer
zones, an environmental impact that negatively affects local livelihoods, was a main reason for the
GEF-IFAD intervention.

Before the start of
the project, greater knowledge on the
specific spots of deforestation was needed. This information will continue to
bebeneficial in the future, when the
impacts of the project need to be evaluated. The European Space Agency financed a project from IFAD preformed by Geoville, to demonstrate how IFAD could benefit from Earth observation data. The project created some interesting
observations on forest coverage in São Tomé and Príncipe.

Earth observation was not an easy task due to the
climatic conditions of the island – most of the time the surface is covered in
fog and clouds. Some areas could only be observed with the help of radar data,
going through clouds but of a lower quality since the clouds lower the view. This
data has been combined with optical data, which has a high quality but does not
show what is under the clouds. These challenges made it impossible to detect
illegal logging on a micro scale.

Although the mapping was far from an easy exercise,
deforestation is clearly seen in the period between 2009-2013. The deforested
regions are painted red on the map to the right. Those areas where
deforestation is observed are mostly near large oil palm and cacao plantations.
Interestingly, these are the same locations that were given to foreign
companies for operation. In addition, there are signals of a shift towards more
heterogeneous and invasive crop cultivation in regions with high deforestation
rates. These findings created a rich source of information on possible causes
of deforestation and provide important inputs for the project.

In the near future, earth observation has even more potential. The European Space Agency will soon
start two new satellite missions that
will generate new datasets of earth observations.[2]
The missions carry a range of technologies, such as radar and
multi-spectral imaging instruments for land, ocean and atmospheric monitoring. The
benefit of these missions is that all data can be accessed for free. This new
open source information will decrease the costs of new mapping exercises.

In addition, maps can be enriched with more precise information,
as in the case of participatory mapping. These maps can include community
information, such as local water stream information or land tenure systems, so
they can be used for specific, local purposes.

The São Tomé and Príncipe
project offers a good example for the practical uses of earth observation
technology by showing where
deforestation has taken place, indicating likely causes of deforestation and
providing a baseline for project evaluation at a later stage. Especially when
one

considers the decreasing costs of
future exercises due to the free data and the possibility of additional applications
to the maps, the potential of earth observations is substantial.